Devitoite

Chemical formula: Ba<sub>6</sub>Fe<sup>2+</sup><sub>7</sub>Fe<sup>3+</sup><sub>2</sub>(Si<sub>4</sub>O<sub>12</sub>)<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>(CO<sub>3</sub>)O<sub>2</sub>(OH)<sub>4</sub>

Dewitoite is an extremely rare, black mineral from the silicate group, known only from one locality in the world in Italy.

## Characteristics Dewitoite is a complex barium and iron silicate, phosphate, and carbonate. It forms very small, thin, platy or lamellar crystals, which usually occur as subparallel or rosette-like aggregates. Its color is uniformly black, and its luster ranges from metallic to submetallic, giving it an appearance similar to some metal ores. ## Physical Properties This mineral is relatively soft, with a hardness of about 4 on the Mohs scale. It is characterized by excellent cleavage in one plane, which makes it brittle and prone to delamination. It is a dense mineral, with a calculated density of 4.19 g/cm³. It is completely opaque. ## Colors and Varieties Dewitoite occurs exclusively in black. No color varieties or commercial varieties are known. ## History and Name The mineral was approved by the IMA in 2009. Its name honors Professor Francesco de Vito (born 1970), an Italian researcher from the University of Pisa, for his contributions to the mineralogy of Tuscany, and in particular his research on minerals from the Cetine di Cotorniano mine, which is the type locality of dewitoite. ## Uses Due to its extreme rarity and occurrence as microscopic crystals, dewitoite has no industrial applications. It is solely an object of scientific interest and is valued by specialized collectors of rare minerals.

Properties

Mohs hardness
4
Luster
Metallic to Sub-Metallic
Streak
Black
Density
4.19
Cleavage
Perfect on {001}
Transparency
Opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Characteristic features of dewitoite include its black color, metallic luster, lamellar or thin-platy crystal habit, and excellent cleavage in one direction. However, a key indicator is its origin – this mineral is known only from one locality in the world. ## Distinguishing from Similar Minerals It can be confused with other black, lamellar minerals, such as hematite, ilmenite, or some micas. However, it is distinguished by its lower hardness, specific mineral parageneses (co-occurrence with other rare minerals, e.g., apuanite), and unique locality. Positive identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Dewitoite forms thin, platy crystals with a hexagonal outline, often grouped into rosette-like or subparallel aggregates. Crystals rarely exceed a fraction of a millimeter in size.

Geological environment

## Genesis Dewitoite forms as a result of low-grade metamorphic processes within lenses of iron ores (mainly hematite) contained in an evaporitic-carbonate rock sequence. Its formation is associated with complex metasomatic processes in a unique chemical environment. ## Mineral Associations This mineral occurs in association with other rare and very rare minerals, such as apuanite, derbylite, saneroite, baryte, quartz, and hematite. ## Localities The only confirmed locality of dewitoite in the world is its type locality – the Cetine di Cotorniano mine (formerly Buca della Vena), near Chiusdino, in the province of Siena, Tuscany, Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of dewitoite specimens, being a typical micromineral, is assessed based on several criteria. The most important is the sharpness and development of crystals within the aggregate. Specimens with distinct, undisturbed crystal rosettes are more highly valued. The abundance of the mineral on the rock matrix and aesthetic associations with other well-formed, rare minerals are also important. ## Popular Localities The most valuable and only available specimens come from the Cetine di Cotorniano mine in Italy. This is the sole source of this mineral on the collector's market.

Care and storage

## Cleaning Dewitoite specimens are extremely delicate and susceptible to mechanical damage due to excellent cleavage. Cleaning should be kept to an absolute minimum. To remove dust, at most a gentle stream of compressed air or a very soft, dry brush can be used. ## What to Avoid Ultrasonic cleaners, all chemical agents, acids, and water should be strictly avoided. Contact with liquids can lead to irreversible damage. The mineral is sensitive to shocks and impacts, which can cause it to break into small lamellae. ## Storage It is recommended to store specimens only in specialized, padded "micromount" boxes, which protect against dust, vibrations, and mechanical damage. Avoid exposure to direct sunlight and sudden temperature changes.

Sources

Read more